Control Box Tests; Check For Grounded Field Coil; Check Continuity Of Terminal Strip Connections; Diode Heat Sink Tests - Komatsu 930E-2 Shop Manual

TEST 4 - Check For Grounded Field Coil
Set ohmmeter to x10K scale and make sure ohmmeter
is zeroed. Connect one ohmmeter lead to terminal "F-"
of the control unit harness. Connect the other ohmme-
ter lead to the front housing ground stud. The ohmme-
ter should read very high. If the ohmmeter reads less
than 100K ohms, the field coil is grounded and must
be replaced (replace or repair Stator & Shell Assem-
bly).
Move ohmmeter lead from "F-" to "F+" (if so equipped),
or to "B+" and repeat test. The ohmmeter should read
very high. If the ohmmeter reads less than 100K ohms,
the field coil is grounded and must be replaced (re-
place or repair Stator & Shell Assembly).

CONTROL BOX TESTS

Note: Needle point probes may be required to pene-
trate the potting compound in the control box.
Refer to Figure 13-4 for location of control box terminal
strip connections. Refer to Figure 13-3 for location of
control box external connections to regulator and igni-
tion circuit.
TEST 5 -

Check Continuity Of Terminal Strip Connections

Set ohmmeter scale according to Table 13-6 and make
ohmmeter connections between the terminal strip in-
side the control box and control box terminals located
on the outside of the control box.
Table 13-6.
CONTROL BOX CONTINUITY CHECKS
TERMINAL
OHMETER STRIP
SCALE CONNECTION
(Figure 13-4)
x10K F-
x1 F-
x1 F+
*GND connections are made to ground terminal
located on outside of front housing.
With regulator disconnected, test for continuity from
"E" terminal on control unit to connector Energize ("E")
pin on regulator harness (See Figure 13-5).
M13-10
CONTROL
BOX
READING
EXTERNAL
CONNECTION
(Figure 13-5)
VERY
GND* (B-)
HIGH
(F-) PIN ZERO
(F+)
ZERO
TERMINAL
Niehoff Alternator Overhaul Manual
FIGURE 13-5.
Metri-Pack Connector
TEST 6 - Diode Heat Sink Tests
Check to make sure that all phase leads are discon-
nected from the heat sink (refer to Figure 13-6).
FIGURE 13-6.
1. Positive Diode Studs
NOTE: Heat sink diodes are de-rated for heavy duty
performance. If diode failure is detected, the entire
charging system should be examined for loose con-
nections (especially battery). If diode failure is indi-
cated, stator failure must also be suspected.
SAE Connector
2. "S" Phase Terminal
M13003 04/01